Pasteurization system and method

ABSTRACT

A pasteurization system includes a liquid inlet configured to receive a liquid to be pasteurized. The system also includes a pump coupled to the liquid inlet for pressurizing the liquid. Further, the system includes a counter flow heat exchanger coupled to the liquid inlet and the pump, the counterflow heat exchanger configured to heat the liquid to a predetermined temperature for at least a predetermined time and configured to exchange heat between a flow of liquid in a first direction in a first channel with the flow of liquid in a second direction opposite the first direction in a second channel. A heating section that heats the liquid flow is integrated into the heat exchanger and heats at least a portion of the first channel or the second channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of theearliest available effective filing date(s) from the following listedapplication(s) (the “Related Applications”) (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC § 119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc. applications of the Related Application(s)).

RELATED APPLICATIONS

-   -   1. For purposes of the USPTO extra-statutory requirements, the        present application relates to U.S. patent application Ser. No.        12/462,213, entitled A SYSTEM AND STRUCTURE FOR HEATING OR        STERILIZING A LIQUID STREAM, naming Geoffrey F. Deane, William        Gates, Roderick A. Hyde, Jordin T. Kare, Nathan P. Myhrvold,        David B. Tuckerman, Lowell L. Wood, Jr. and Ozgur Yildirim as        inventors, filed contemporaneously herewith, which is currently        co-pending, or is an application of which a currently co-pending        application is entitled to the benefit of the filing date.    -   2. For purposes of the USPTO extra-statutory requirements, the        present application relates to U.S. patent application Ser. No.        12/462,200, entitled A METHOD FOR HEATING OR STERILIZING A        LIQUID STREAM, naming Geoffrey F. Deane, William Gates,        Roderick A. Hyde, Jordin T. Kare, Nathan P. Myhrvold, David B.        Tuckerman, Lowell L. Wood, Jr. and Ozgur Yildirim as inventors,        filed contemporaneously herewith, which is currently co-pending,        or is an application of which a currently co-pending application        is entitled to the benefit of the filing date.

The United States Patent Office (USPTO) has published a notice to theeffect that the USPTO's computer programs require that patent applicantsreference both a serial number and indicate whether an application is acontinuation or continuation-in-part. Stephen G. Kunin, Benefit ofPrior-Filed Application, USPTO Official Gazette Mar. 18, 2003, availableat http://www.uspto.gov/web/offices/com/sol/og/2003/week11/patbene.htm.The present Applicant Entity (hereinafter “Applicant”) has providedabove a specific reference to the application(s) from which priority isbeing claimed as recited by statute. Applicant understands that thestatute is unambiguous in its specific reference language and does notrequire either a serial number or any characterization, such as“continuation” or “continuation-in-part,” for claiming priority to U.S.patent applications. Notwithstanding the foregoing, Applicantunderstands that the USPTO's computer programs have certain data entryrequirements, and hence Applicant is designating the present applicationas a continuation-in-part of its parent applications as set forth above,but expressly points out that such designations are not to be construedin any way as any type of commentary and/or admission as to whether ornot the present application contains any new matter in addition to thematter of its parent application(s).

All subject matter of the Related Applications and of any and allparent, grandparent, great-grandparent, etc. applications of the RelatedApplications is incorporated herein by reference to the extent suchsubject matter is not inconsistent herewith.

BACKGROUND

The description herein generally relates to the field of ultra-hightemperature (UHT) pasteurization. Pasteurization and UHT pasteurizationhas been used to at least partially sterilize milk and other foodproducts. However, conventional pasteurization and conventional UHTpasteurization has been limited to applications in which substantialpower is readily available for the pasteurizing process.

There is a need for advantageous structures and methods for performingUHT pasteurization which consumes substantially less power thanconventional techniques by the use of microchannels and the like in avariety of structures and in a variety of usage.

SUMMARY

In one aspect, a pasteurization system includes a liquid inletconfigured to receive a liquid to be pasteurized. The system alsoincludes a pump coupled to the liquid inlet for pressurizing the liquid.Further, the system includes a counter flow heat exchanger coupled tothe liquid inlet and the pump, the counterflow heat exchanger configuredto heat the liquid to a predetermined temperature for at least apredetermined time and configured to exchange heat between a flow ofliquid in a first direction in a first channel with the flow of liquidin a second direction opposite the first direction in a second channel.A heating section that heats the liquid flow is integrated into the heatexchanger and heats at least a portion of the first channel or thesecond channel.

In addition to the foregoing, other method aspects are described in theclaims, drawings, and text forming a part of the present disclosure.

In one or more various aspects, various structural elements may beemployed depending on design choices of the system designer.

In one aspect, a pasteurization system includes a liquid inletconfigured to receive a liquid to be pasteurized. The system alsoincludes a pump coupled to the liquid inlet for pressurizing the liquid.Further, the liquid includes a microchannel heat exchanger coupled tothe liquid inlet and the pump. The microchannel heat exchanger hasmicrochannels and is configured to heat the liquid to a predeterminedtemperature for at least a predetermined time and is configured toexchange heat between flows of liquid. The channels of the microchannelheat exchanger have a hydraulic diameter, expressed as four times thecross sectional area of the channel divided by the perimeter of thecross section, that is less than approximately one millimeter.

In yet another aspect, an ultra-high temperature milk pasteurizationsystem includes a liquid inlet configured to receive milk to bepasteurized. The system also includes a pump coupled to the liquid inletfor pressurizing the liquid. Further, the system includes a counter flowheat exchanger coupled to the liquid inlet and the counterflow heatexchanger configured to heat the milk to a temperature of at least 135degrees Celcius for at least a period of one tenth of a second.

In a further aspect, a pasteurization system includes a liquid inletconfigured to receive a liquid to be pasteurized. The system alsoincludes a pump coupled to the liquid inlet for pressurizing the liquid.The system further includes a counter flow heat exchanger coupled to theliquid inlet and the pump. The counterflow heat exchanger is configuredto heat the liquid to a predetermined temperature for at least apredetermined time and configured to exchange heat between a flow ofliquid in a first direction in a first channel with the flow of liquidin a second direction opposite the first direction in a second channel.A heating section heats the liquid flow in at least one of the firstchannel and the second channel.

In still yet another aspect, a pasteurization system includes a liquidinlet configured to receive a liquid to be pasteurized. The system alsoincludes a pump coupled to the liquid inlet for pressurizing the liquid.Further, the system includes a microchannel heat exchanger coupled tothe liquid inlet and the pump. The microchannel heat exchanger isconfigured to heat the liquid to a predetermined temperature for atleast a predetermined time and is configured to exchange heat betweenflows of liquid. The channels of the microchannel heat exchanger areconfigured to produce substantially laminar flow within the channels.

In addition to the foregoing, other system aspects are described in theclaims, drawings, and text forming a part of the present disclosure.

In addition to the foregoing, various other method and/or system and/orprogram product aspects are set forth and described in the teachingssuch as text (e.g., claims and/or detailed description) and/or drawingsof the present disclosure.

The foregoing is a summary and thus contains, by necessity,simplifications, generalizations and omissions of detail; consequently,those skilled in the art will appreciate that the summary isillustrative only and is NOT intended to be in any way limiting. Otheraspects, features, and advantages of the devices and/or processes and/orother subject matter described herein will become apparent in theteachings set forth herein.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description, of which:

FIG. 1 is an exemplary depiction of a food product sterilization system.

FIG. 2 is an exemplary depiction of a counterflow heat exchanger.

FIG. 3 is an exemplary depiction of an exploded view of a heat exchangerchannel pair.

FIG. 4 is an exemplary depiction of a heat exchanger showing axial heatleakage.

FIG. 5 is an exemplary depiction of a heat exchanger showing temperatureprofiles and heat flow between adjacent channels.

FIG. 6 is an exemplary depiction of a heat exchanger showing radial heatleakage.

FIG. 7 is an exemplary depiction of a heat exchanger showing heatleakage through an insulating wrap.

FIG. 8 is an exemplary depiction of heat exchanger channel spacers.

FIG. 9 is an exemplary depiction of a method of forming heat exchangerchannel spacers.

FIG. 10 is an exemplary depiction of a method of forming heat exchangerchannel spacers.

FIG. 11. is an exemplary depiction of an alternative counterflow heatexchanger.

FIG. 12 is an exemplary depiction of an alternative counterflow heatexchanger.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. Those having skill in the art will recognize that thestate of the art has progressed to the point where there is littledistinction left between hardware and software implementations ofaspects of systems; for example the use of hardware or software isgenerally (but not always, in that in certain contexts the choicebetween hardware and software can become significant) a design choicerepresenting cost vs. efficiency tradeoffs. Those having skill in theart will appreciate that there are various vehicles by which processesand/or systems and/or other technologies described herein can beeffected (e.g., hardware, software, and/or firmware), and that thepreferred vehicle will vary with the context in which the processesand/or systems and/or other technologies are deployed. For example, ifan implementer determines that speed and accuracy are paramount, theimplementer may opt for a mainly hardware and/or firmware vehicle;alternatively, if flexibility is paramount, the implementer may opt fora mainly software implementation; or, yet again alternatively, theimplementer may opt for some combination of hardware, software, and/orfirmware. Hence, there are several possible vehicles by which theprocesses and/or devices and/or other technologies described herein maybe effected, none of which is inherently superior to the other in thatany vehicle to be utilized is a choice dependent upon the context inwhich the vehicle will be deployed and the specific concerns (e.g.,speed, flexibility, or predictability) of the implementer, any of whichmay vary. Those skilled in the art will recognize that optical aspectsof implementations will typically employ optically-oriented hardware,software, and or firmware.

Pasteurization is a process that is conventionally used to slowmicrobial growth in food. Pasteurization is a type of sterilizationprocess that is generally not intended to kill all pathogenicmicro-organisms in the food or liquid. Instead, pasteurization aims toreduce the number of viable pathogens so they are unlikely to causedisease (assuming the pasteurization product is refrigerated andconsumed before its expiration date). However, although much focus ofthe description may be on pasteurization processes and more particularlyon ultra-high temperature pasteurization processes, the subject matterherein disclosed may be applied both to pasteurization as well as othersterilization processes, whether they be complete or incomplete.

Pasteurization conventionally uses temperatures below boilingtemperatures since at temperatures above the boiling point for milk,e.g., casein micelles will irreversibly aggregate (or “curdle”). Thereare three main types of pasteurization used today: HighTemperature/Short Time (HTST), Extended Shelf Life (ESL) treatment, andultra-high temperature (UHT or ultra-heat treated) is also used for milktreatment. In the HTST process, milk is forced between metal plates orthrough pipes heated on the outside by hot water, and is heated to 71.7°C. (161° F.) for 15-20 seconds. UHT processing holds the milk at atemperature of approximately 135° C. (275° F.) for a time period rangingfrom a fraction of a second to a couple of seconds; this temperature isabove the boiling point of milk at normal atmospheric pressures, butboiling can be suppressed by operating at a pressure substantially aboveatmospheric pressure. The use of a short exposure time minimizes thedetrimental effects on taste and protein constituents that wouldnormally occur at 135° C. ESL milk has a microbial filtration step andlower temperatures than HTST.

There exist many food products that may be pasteurized. These foodproducts include but are not limited to beer, cider, fruit juice, maplesyrup, milk, wine, soy sauce, sports drinks, water, etc.

In regions including Africa and South Asian countries, it is common toboil milk to sterilize it after it is harvested. This intense heatinggreatly changes the flavor of milk and may require a substantial amountof energy, which may be limited. Some of the diseases that boiling of orpasteurization may prevent include but are not limited to tuberculosis,diphtheria, salmonellosis, strep throat, scarlet fever, listeriosis andtyphoid fever.

UHT pasteurization is the partial sterilization of food by heating itfor a short time, around 1-2 seconds, at a temperature exceeding 135° C.(275° F.), which is the temperature required to kill spores some sporeswhich may be found in milk. The most common UHT product is milk, but theprocess is also used for fruit juices, cream, yogurt, wine, soups, andstews, etc.

Advantageously, UHT milk has a typical shelf life of six to nine months,until opened, which is higher than provided by traditionallower-temperature pasteurization processes.

Referring now to FIG. 1, an exemplary system 100 for pasteurizing (oralternatively sterilizing) milk or other food products or liquids, isdepicted. Such liquids may include but are not limited colloids andsuspensions, etc. System 100 includes a fluid inlet 110 for introducingthe food product or other liquid. A filter 120 receives the fluid andfilters any particulate or other solids from the fluid. Filter 120 feedsinto a pump 130 that pressurizes the fluid in system 100. Pump 130 maybe, but is not limited to, a positive displacement pump that is run by aDC motor with a preset or controllable speed. Pump 130 feeds the fluidinto a heat exchanger 140. In accordance with an exemplary embodimentheat exchanger 140 may be a microchannel heat exchanger having fluidchannels with a high aspect ratio, small hydraulic diameter, and othercharacteristics similar to other microchannel devices such as but notlimited to microchannel coolers for cooling integrated circuits,solid-state lasers, and the like. Heat exchanger 140 includes a heater150 which heats a portion of heat exchanger 140 and the fluid flowingtherethrough such that the fluid reaches the UHT pasteurizationtemperature or other predetermined temperature for a predetermined time,such as but not limited to 1-2 seconds. Heat exchanger 140 includes aheat exchanger outlet 160 that feeds into a pressure relief valve 170,which in an exemplary embodiment will not open unless the pressurereaches a predetermined pressure, such as but not limited to 37 psi.Such fluid is released through a sterile output 180 into sterilereceptacles or packages. Heat exchanger 140 may be at least partiallyencased by an insulating layer 190 which may be but is not limited to avacuum jacket, or a chamber of Xenon gas, or an aerogel foam, or otherinsulating material.

Microchannels have been proposed to cool integrated circuits and havebeen understood since the early 1980s and disclosed in researchpublished by Dr. David Tuckerman and Prof. R. Fabian Pease. Tuckermanand Pease published research showing that microchannels etched intosilicon may provide densities as high as 1000 W per square centimeter.Such microchannel structures have been shown to be capable of coolingintegrated circuits, such as described in U.S. Pat. Nos. 4,541,040;7,156,159; 7,185,697; and U.S. Patent Application Publication No.2006/0231233 all of which are herein incorporated by reference. However,practical application to pasteurization, sterilization, or transientheating of a fluid flow has not been accomplished or suggested.

One of the advantages of using the microchannel structures is thatturbulent flow within the channels is not necessary to increase heattransfer efficiency. Microchannel structures neither require nor createturbulent flow. Conventional macrochannels require turbulence toincrease heat transfer rate, otherwise the fluid acts as an insulatorbetween the channel wall and the center of the fluid flow, which isknown as a thermal boundary layer. Turbulent flow within the fluidchannel mixes the fluid next to the wall of the channel with the fluidin the middle of the channel, thereby minimizing the thickness of thethermal boundary layer and maximizing the rate of heat transfer betweenthe fluid and the wall. However, such turbulence and mixing requireshigh flow velocities and high pressures. In addition, the high flowvelocities would require that the heat exchanger channels be very longin order to achieve the 2-second residence time at 135° C. recommendedfor UHT sterilization. Microchannels, instead, have the advantage thatthe heat transfer coefficient “h” is inversely proportional to the widthof the channel. As “h” increases, efficiency increases. A very narrowchannel has a thin thermal boundary layer, because the boundary layercannot be larger than ½ the channel width. Thus, heat is transferredbetween the wall and the center of the channel with very little thermalresistance. Accordingly, it may be beneficial to use a microchannel ormicrochannel-like heat exchanger for UHT pasteurization in order toincrease heat transfer and therefore enable a very compact design thatrequires a relatively low energy input.

Referring now to FIG. 2, an exemplary perspective cross-section of acounterflow heat exchanger 200, which may be used as heat exchanger 140of FIG. 1. Heat exchanger 200 includes a stack of flow channels. Stackof flow channels includes a repeated series of inflow channels 210alternating with outflow channels 220. In such a counterflow heatexchanger, the fluid preferably makes a roundtrip in channel 210 and outof an adjacent channel 220, i.e., the heat exchanger is single-endedwith its inputs and outputs at or near the same end. In an advantageousdesign, excellent heat transfer between channels 210 and 220 is desiredwhile axial heat transfer along the length of the channels is notdesired.

Referring now to FIG. 3, an exemplary exploded view of a channel pair300 from a counterflow heat exchanger such as but not limited to heatexchanger 200 is depicted. Channel pair 300 includes an inflow channel310 that includes a slot 315 that fluidly couples channel 310 to channel320. Channel 320 includes an outlet 325. In an exemplary embodiment, thechannels may include thermally conductive plating 330 such as but notlimited to Copper or Aluminum plating on a portion of the channels forconducting or applying a heat input to the fluid flow in the channelsand maintaining an approximately uniform high temperature over asubstantial length of the heat exchanger. In accordance with anexemplary embodiment, the side walls may be on the order of 40-50microns thick and the base may be on the order of 10-12 microns thick,however the heat exchanger is not limited to these dimensions. In anexemplary embodiment, the heat exchanger may include, but is not limitedto, approximately 100 or more of these pairs in stacked relation. Inaccordance with one exemplary embodiment, the channels may be formed ofpolyaryletheretherketone (PEEK).

Referring now to FIG. 4, a further exemplary depiction of theaforementioned counterflow heat exchanger is depicted. Heat exchanger400 includes a hot zone 410 in which heat input is applied and a heat-up(for inflows)/cool down (for outflows) zone 420 where much of the heatexchange occurs. An exemplary graph 430 depicts the approximatetemperature profile of the fluid flows along the length of the heatexchanger.

With reference to FIG. 5, a depiction of the residual heat in theexiting fluid is provided in graph 530. Such an exemplary depictionillustrates the temperature profiles of both the input and output fluidflow, with the heat exchanger thermodynamic irreversibility illustratedby the temperature increase δT in the exit fluid temperature relativelyto the inlet fluid temperature. Said thermodynamic irreversibilityrepresents the minimum thermal energy that must be supplied to the heatexchanger (e.g., to the hot zone) in order to maintain the desired hotzone temperature. Additional energy will be required to overcomeparasitic heat leaks such as the axial heat leak illustrated by thearrow labeled ‘heat flow’ in FIG. 4. An additional heat leak in theradial directions (i.e., outward heat flows in the plane perpendicularto the direction of flow) are illustrated by the arrows 630 in FIG. 6emanating from heat exchanger 400. FIG. 7 depicts the use of aninsulative wrap 730 which may be formed of a variety of materialsincluding but not limited to aerogel, silica aerogel, or Xenon gas,among many other insulation materials. The magnitude of radial heatflows 630 will be reduced in comparison with those in FIG. 6 by virtueof the thermal insulation layer, thereby reducing the thermal energyinput required to maintain the hot zone temperature.

In accordance with an exemplary embodiment, as depicted in FIG. 8, itmay be desirable to use 10 or 12 micron PEEK film to construct thechannel walls 810 of the heat exchanger. Other thicknesses or othermaterials with relatively poor thermal conductivity, such as stainlesssteel, may be equally applicable depending on the desiredcharacteristics. Each of the channel walls may be spaced apart and keptspaced apart by a plurality of spacers 820 which aid in maintaining thechannel height in opposition to the pressure differentials between inletand outlet channels which will exist during operation of thepasteurizer. These spacers 820 may be in the form of ribs or spheres (asdepicted) which are pressed onto the film 810 or otherwise attached orformed. Such spacers may preferably be thermally conductive in nature toaid in the heat transfer in the transverse direction, but preferably arenon-contiguous in the flow (axial) direction so as to minimize the heattransfer in the axial direction along the length of the heat exchanger.In one preferred embodiment, the spacers in each layer are offset inhorizontal location from those in the two immediate adjacent layers. Inanother embodiment, the spacers are configured in a denser pattern nearthe input/output ends of the heat exchanger, where the pressuredifferential between adjacent channels is high, and configured in asparser pattern near the hot zone, where the pressure differentialbetween input and output channels is low.

Referring now to FIG. 9, a method 900 of fabricating heat exchangerchannels is depicted. In the exemplary embodiment, an aluminum or copperfoil (on the order of 52 microns thick) 910 is adhered to a tape backing920 (process 930). Using photolithography and etching techniquesmaterial is removed leaving behind aluminum or copper posts 940 adheredto the tape backing 920 (process 950). The copper posts 940 and tapebacking 950 are inverted and placed between plates 960 of a hot press.The posts 940 are pressed into a sheet of PEEK 970 (process 980). Thehot press plates 960 and the tape backing 920 are removed leaving behinda sheet of PEEK 970 with posts 940 to provide spacing and support for aheat exchanger to be assembled from stacked layers of these (process990).

Referring now to FIG. 10, an alternative method 1000 of forming a spacerarray to be fabricated using a 300 micron metal sheet 1010 havingdepressions 1015 is depicted (process 1020). The depressions or cavities1015 are populated with metal spheres 1030 using a shaker table or othermethods (process 1040). PEEK film 1060 is overlaid on the metal spheres1030 and hot pressed using an upper mandrel 1050 (process 1070). ThePEEK is removed from the press and the spheres remain embedded in thePEEK (process 1080) to be formed into the heat exchanger.

In yet another exemplary embodiment, an alternative manufacturingtechnique 1100 is depicted in FIG. 11 which does not require thehandling of 100 or more individual piece parts. A first channel and asecond channel running adjacent one another are formed from a singlestrip or ribbon of PEEK material 1110 by folding over the material onitself to form a stack of channels pairs of which are linked by slots1120. Other concepts for manufacturing the heat exchanger and materialsthat are applicable may also be used.

Referring now to FIG. 12, a double-ended pass through heat exchanger1200 is depicted. Pass through heat exchanger 1200 includes channels1210 having flow in one direction through a heater 1230. Flow throughchannel 1210 receives heat input from flow 1220 in the oppositedirection before entering heater 1230. Flow through channel 1210provides heat to flow 1220 after flowing through heater 1230. In theexemplary embodiment, the fluid flows through channels 1210 and 1220simultaneously in an interleaved configuration, and does not make aroundtrip as in the exemplary embodiments described above. This passthrough heat exchanger therefore may have the advantage in eliminatingturns in the fluid flow channel. In a preferred embodiment, the massflow rates going in one direction are closely controlled so as to beequal and opposite to the mass flow rates going in the oppositedirection.

In one exemplary embodiment, the input and output channels are separatedby a thin wall having a thickness in the range of about 0.01 centimetersto 0.001 centimeters. Although these thicknesses may be desirable, otherthicknesses may be used. With the heat exchanger provided above, it maybe desirable to construct it in such a manner that at least 90% of theheat input is provided by a heater that is thermally coupled to the hotzone. In one exemplary embodiment the input channel and the outputchannels each have a hydraulic diameter that is less than approximatelyone millimeter, where the hydraulic diameter is four times the crosssectional area of the channel divided by the perimeter of the crosssection. In one exemplary embodiment a highly conductive material isdisposed between the heater and the channel. In accordance with anexemplary embodiment, the highly conductive material may be copper,other metals or metal alloys or other highly conductive materials. Inaccordance with an exemplary embodiment, a sensor may be used to senseat least one characteristic of the food product. The sensor may be butis not limited to a temperature transducer, a pressure transducer, aflow transducer, etc.

The use of a sensor allows for the closed loop controllability of thesterilizer system. In an exemplary embodiment computer or microprocessorcontrollers may be implemented to control temperature, heater, pump,fluid flow, valves, etc. Such a controller may use any of a variety ofalgorithms and employ any type of applicable hardware and softwarecomponents.

In accordance with an exemplary embodiment, the heating structure in theheat exchanger includes a heating element with highly conductivematerials to transfer the heat to the fluid channels. Alternatively,active heating structures may be coupled directly to the microchannelsinstead of using the highly conductive materials to transfer the heat.

In many of the exemplary embodiments disclosed, it has been contemplatedto use the heat exchanger for sterilization of food products. However,the heat exchanger structure may also be used in other applicationsincluding but not limited to various types of brewing applications,making yogurt, fermentation processes, sustaining or participating in achemical or biological reaction, etc. Further, in an exemplaryembodiment the heat exchanger may be used in polymerase chain reaction(PCR) processes for the rapid duplication of DNA.

The heat exchanger described above is contemplated to increaseefficiency during a transient heating process. In accordance with anexemplary embodiment the heat exchanger may be designed to heat milk orwater to a temperature of approximately 135 degrees C. and hold it atthat temperature for approximately 2 seconds and then cool down thefluid while recovering the vast majority of the heat such that energyinput is minimal compared with conventional UHT pasteurizationprocesses. In accordance with an exemplary embodiment it is advantageousto maintain axial heat flow (along the flow path) to a minimum whilemaximizing heat transfer between the channels in an attempt to maximizeefficiencies of the heat exchanger.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. Further, those skilledin the art will recognize that the mechanical structures disclosed areexemplary structures and many other forms and materials may be employedin constructing such structures.

In a general sense, those skilled in the art will recognize that thevarious embodiments described herein can be implemented, individuallyand/or collectively, by various types of electro-mechanical systemshaving a wide range of electrical components such as hardware, software,firmware, or virtually any combination thereof; and a wide range ofcomponents that may impart mechanical force or motion such as rigidbodies, spring or torsional bodies, hydraulics, and electro-magneticallyactuated devices, or virtually any combination thereof. Consequently, asused herein “electro-mechanical system” includes, but is not limited to,electrical circuitry operably coupled with a transducer (e.g., anactuator, a motor, a piezoelectric crystal, etc.), electrical circuitryhaving at least one discrete electrical circuit, electrical circuitryhaving at least one integrated circuit, electrical circuitry having atleast one application specific integrated circuit, electrical circuitryforming a general purpose computing device configured by a computerprogram (e.g., a general purpose computer configured by a computerprogram which at least partially carries out processes and/or devicesdescribed herein, or a microprocessor configured by a computer programwhich at least partially carries out processes and/or devices describedherein), electrical circuitry forming a memory device (e.g., forms ofrandom access memory), electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment), and any non-electrical analog thereto, such as optical orother analogs. Those skilled in the art will also appreciate thatexamples of electro-mechanical systems include but are not limited to avariety of consumer electronics systems, as well as other systems suchas motorized transport systems, factory automation systems, securitysystems, and communication/computing systems. Those skilled in the artwill recognize that electro-mechanical as used herein is not necessarilylimited to a system that has both electrical and mechanical actuationexcept as context may dictate otherwise.

Those skilled in the art will recognize that it is common within the artto implement devices and/or processes and/or systems in the fashion(s)set forth herein, and thereafter use engineering and/or businesspractices to integrate such implemented devices and/or processes and/orsystems into more comprehensive devices and/or processes and/or systems.That is, at least a portion of the devices and/or processes and/orsystems described herein can be integrated into other devices and/orprocesses and/or systems via a reasonable amount of experimentation.

One skilled in the art will recognize that the herein describedcomponents (e.g., steps), devices, and objects and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are within theskill of those in the art. Consequently, as used herein, the specificexemplars set forth and the accompanying discussion are intended to berepresentative of their more general classes. In general, use of anyspecific exemplar herein is also intended to be representative of itsclass, and the non-inclusion of such specific components (e.g., steps),devices, and objects herein should not be taken as indicating thatlimitation is desired.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.Furthermore, it is to be understood that the invention is defined by theappended claims. It will be understood by those within the art that, ingeneral, terms used herein, and especially in the appended claims (e.g.,bodies of the appended claims) are generally intended as “open” terms(e.g., the term “including” should be interpreted as “including but notlimited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

The invention claimed is:
 1. A pasteurization system, comprising: aliquid inlet configured to receive a liquid to be pasteurized; a pumpcoupled to the liquid inlet for pressurizing the liquid; and a counterflow heat exchanger coupled to the liquid inlet and the pump, thecounter flow heat exchanger including at least a first channel and asecond channel fluidly coupled in hydraulic communication with the firstchannel within the counter flow heat exchanger, wherein the firstchannel and the second channel are microchannels, the second channelbeing hydraulically coupled to receive the same liquid from the firstchannel such that the first channel and the second channel arehydraulically coupled to direct flow of the same liquid, the counterflow heat exchanger configured to heat the liquid to a predeterminedtemperature for at least a predetermined time and configured to exchangeheat between a flow of the liquid in a first direction in the firstchannel with the flow of the liquid in the second direction opposite thefirst direction in a second channel, where the liquid is flowable fromthe first channel into the second channel, the counter flow heatexchanger including a heating section including an electric heater thatprovides a heat input and heats the liquid flow, the electric heaterbeing disposed in thermal communication with at least a portion of thefirst channel or the second channel to heat at least the portion of thefirst channel or the second channel with the heat input from theelectric heater, wherein an insulative layer at least partiallyinsulates the first channel and the second channel; and a heat exchangeroutlet that feeds into a pressure relief valve.
 2. The pasteurizationsystem of claim 1, wherein the first channel and the second channel areseparated by a thin wall.
 3. The pasteurization system of claim 1,wherein the first channel and the second channel are separated by a thinwall and the thin wall has a thickness less than 0.01 centimeters. 4.The pasteurization system of claim 1, wherein the first channel and thesecond channel are separated by a thin wall and the thin wall has athickness less than 0.002 centimeters.
 5. The pasteurization system ofclaim 1, wherein the first channel and the second channel share a wall.6. The pasteurization system of claim 1, wherein the first channel andthe second channel share a wall and there exist multiple pairs of inputchannels and output channels in a row each pair sharing a wall with anadjacent pair.
 7. The pasteurization system of claim 6, wherein theinput and output channels are at least partially surrounded by aninsulating layer.
 8. The pasteurization system of claim 1, wherein thefirst and second channels each have a hydraulic diameter, each hydraulicdiameter expressed as four times the cross sectional area of each of thefirst and second channels divided by the perimeter of the respectivecross section, each hydraulic diameter being less than one millimeter.9. The pasteurization system of claim 1, wherein the first channel andthe second channel are at least partially formed ofpolyaryletheretherketone.
 10. The pasteurization system of claim 1,wherein the heating section includes at least one of copper and aluminumplating between the heater and the channel.
 11. The pasteurizationsystem of claim 1, wherein the heating section includes at least one ofcopper and aluminum plating between the heater and at least the secondchannel.
 12. The pasteurization system of claim 1, wherein the liquid tobe pasteurized includes at least one of fruit juice, apple cider, honey,maple syrup, milk, soy sauce, sports drinks, vinegar, water, wine, beer,cream, and cheese.
 13. The pasteurization system of claim 1, furthercomprising a filter configured to filter the liquid, the filter coupledto the inlet.
 14. The pasteurization system of claim 1, wherein thefirst channel and the second channels are configured with aspect ratioswhich produce substantially laminar flow.
 15. The pasteurization systemof claim 1, wherein the first channel and the second channels areconfigured to induce liquid flow in the channel with a boundary layerthickness that is greater than one-half the thickness of the channel.16. The pasteurization system of claim 1, wherein the insulative layerat least partially insulates the heating section.
 17. The pasteurizationsystem of claim 1, wherein the heat exchanger includes multiple pairs offirst channels and second channels.
 18. The pasteurization system ofclaim 1, wherein a first channel is adjacent to and receives heat frommultiple second channels.
 19. The pasteurization system of claim 1,wherein a second channel is adjacent to and transfers heat to multiplefirst channels.
 20. The pasteurization system of claim 1, wherein thereare multiple first channels and second channels and the first channelsalternate with the second channels in a side-to-side relationship. 21.The pasteurization system of claim 1, further comprising supportelements within at least one of the first channels and the secondchannels.
 22. A pasteurization system, comprising: a liquid inletconfigured to receive a liquid to be pasteurized; a pump coupled to theliquid inlet for pressurizing the liquid; a microchannel heat exchangercoupled to the liquid inlet and the pump, the microchannel heatexchanger having microchannels and configured to heat the liquid to apredetermined temperature for at least a predetermined time andconfigured to exchange heat between flows of the same liquid where themicrochannels are fluidly coupled in pairs in hydraulic communicationwith each other within the microchannel heat exchanger so that the sameliquid is flowable from one of the microchannels into another of themicrochannels fluidly coupled therewith within the microchannel heatexchanger and so that heat in one portion of the flow is transferred toanother part of the flow of the same liquid, the microchannels of themicrochannel heat exchanger each having a hydraulic diameter, thehydraulic diameter expressed as four times the cross sectional area ofthe respective microchannel divided by the perimeter of the crosssection of the respective microchannel, the hydraulic diameter beingless than one millimeter, the microchannel heat exchanger having aheating section including an electric heater that provides a heat inputand heats the liquid flow, the electric heater being disposed in thermalcommunication with a portion of the pairs of microchannels and heatingat least a portion of the pairs of microchannels with the heat inputfrom the electric heater, wherein an insulative layer at least partiallyinsulates the pairs of microchannels; and a heat exchanger outlet thatfeeds into a pressure relief valve.
 23. The pasteurization system ofclaim 22, wherein the heat exchanger is regenerative.
 24. Thepasteurization system of claim 22, wherein the liquid flows are counterflowing.
 25. The pasteurization system of claim 22, wherein the heatexchanged is between different portions of the same liquid flow.
 26. Anultra-high temperature milk pasteurization system, comprising: a liquidinlet configured to receive milk to be pasteurized; a pump coupled tothe liquid inlet for pressurizing the milk; a counter flow heatexchanger having adjacent microchannels fluidly coupled in hydrauliccommunication with each other within the counter flow heat exchanger,the counter flow heat exchanger coupled to the liquid inlet andconfigured to flow the same milk through one of the adjacentmicrochannels into the other of the adjacent microchannels fluidlycoupled therewith within the counter flow heat exchanger and the counterflow heat exchanger configured to heat the milk to a temperature of atleast 135 degrees Celcius for at least a period of one tenth of asecond, the counter flow heat exchanger having a heating sectionincluding an electric heater that provides a heat input and heats themilk flow, the electric heater being disposed in thermal communicationwith a portion of one of the adjacent microchannels or the other of theadjacent microchannels and heating at least a portion of one of theadjacent microchannels or the other of the adjacent microchannels withheat input from the electric heater, wherein an insulative layer atleast partially insulates the adjacent microchannels; and a heatexchanger outlet that feeds into a pressure relief valve.
 27. Theultra-high temperature milk pasteurization system of claim 26, whereinthe heat exchanger is regenerative.
 28. The ultra-high temperature milkpasteurization system of claim 26, wherein the heat exchanged is betweendifferent portions of the same milk flow.
 29. A pasteurization system,comprising: a liquid inlet configured to receive a liquid to bepasteurized; a pump coupled to the liquid inlet for pressurizing theliquid; and a counter flow heat exchanger having a first microchanneland a second microchannel coupled to the liquid inlet and the pump, thefirst microchannel and the second microchannel being fluidly coupled inhydraulic communication with each other within the counter flow heatexchanger, the counter flow heat exchanger configured to heat the liquidto a predetermined temperature for at least a predetermined time andconfigured to exchange heat between a flow of liquid in the firstdirection in the first microchannel with the flow of the same liquid inthe second direction opposite the first direction in the secondmicrochannel, where the same liquid is flowable from the firstmicrochannel into the second microchannel within the counter flow heatexchanger, the counter flow heat exchanger having a heating sectionincluding an electric heater that provides a heat input and heats theliquid flow in at least one of the first microchannel and the secondmicrochannel, the electric heater being disposed in thermalcommunication with at least a portion of at least one of the firstmicrochannel and the second microchannel and heating at least a portionof at least one of the first microchannel and the second microchannelwith the heat input from the electric heater, wherein an insulativelayer at least partially insulates the first microchannel and the secondmicrochannel; and a heat exchanger outlet that feeds into a pressurerelief valve.
 30. A pasteurization system, comprising: a liquid inletconfigured to receive a liquid to be pasteurized; a pump coupled to theliquid inlet for pressurizing the liquid; a microchannel heat exchangerhaving multiple microchannels coupled to the liquid inlet and the pump,the microchannel heat exchanger configured to heat the liquid to apredetermined temperature for at least a predetermined time andconfigured to exchange heat between flows of the same liquid where themicrochannels are fluidly coupled in pairs in hydraulic communicationwith each other within the microchannel heat exchanger so that theliquid is flowable from one of the microchannels into another of themicrochannels fluidly coupled therewith within the microchannel heatexchanger and so that heat in one portion of the flow of the liquid istransferred to another part of the flow of the same liquid, themicrochannels of the microchannel heat exchanger being configured toproduce substantially laminar flow within the microchannels, themicrochannel heat exchanger having a heating section including anelectric heater that provides a heat input and heats the liquid flow,the electric heater being disposed in thermal communication with atleast a portion of the pairs of microchannels and heating at least aportion of the pairs of microchannels with the heat input from theelectric heater, wherein an insulative layer at least partiallyinsulates the pairs of microchannels; and a heat exchanger outlet thatfeeds into a pressure relief valve.
 31. The pasteurization system ofclaim 30, wherein the heat exchanger is regenerative.
 32. Thepasteurization system of claim 30, wherein the liquid flows are counterflowing.
 33. The pasteurization system of claim 30, wherein the heatexchanged is between different portions of the same liquid flow.